This invention relates to radiant tube heaters and burner and heating assemblies for use therewith.
A known type of radiant heater for heating the interior of buildings and other areas is a so-called radiant tube heater which has a relatively long, radiant tube made of a suitable metal and adapted to enclose an elongate flame projected from a burner head. This heater can include a combustion air blower, a burner nozzle connected to a combustible gas supply, and a burner head connected to the nozzle. The nozzle and head are positioned in a combustion air duct section forming a passage for combustion air and the outlet of the blower is attached to an inlet end of this duct section so that the blower is able to direct combustion air through the duct section. The burner head which in an exemplary embodiment is arranged centrally in the air duct section, creates an annular passageway between itself and the air duct section. Combustible gas, such as natural gas, can be delivered to the radiant heater through a gas valve governor which is connected by a line to the burner nozzle. Combustion air enters the burner head through vents or ports in the side wall of an inlet portion of the head and then mixes with the fuel, thereby producing a gas/air mixture which can exit through a perforated ceramic tile mounted in a downstream end of the head. The mixture can be ignited by a suitable electrode resulting in a long laminer flame extending down the radiant tube.
One form of radiant tube heater is described and illustrated in co-pending U.S. patent application Ser. No. 11/831,130 filed Jul. 31, 2007 and the disclosure and drawings of this co-pending application are incorporated herein by reference. This radiant tube heater in addition to including the aforementioned features, employs a tubular arrangement that includes an air duct portion forming a combustion air passage and a radiant tube portion which is heated. An airflow restricting plate is mounted in the air duct portion and extends circumferentially around the burner head. This plate can increase the flow of pressurized combustion air through the openings formed in the inlet portion of the burner head while also allowing a substantial portion of the combustion air to flow downstream between the wider outlet portion of the head and the air duct portion to provide secondary air for combustion.
The blower for the aforementioned radiant tube heater has a blower housing with a relatively straight, outlet section. Mounted on an outer wall of this outlet section are two pressure sensors in the form of pitot tubes of standard construction. These sensors are connected to differential pressure switches to ensure that the blower is in operation and is providing sufficient combustion air to the burner head when the mixture of combustion air and gas is ignited. The heater is constructed so as not to operate unless sufficient combustion air is being provided to the heater.
There is disclosed herein an air diverter for a radiant tube heater of the above-mentioned type which is mounted at or near an upstream end of the burner head which, in addition to imparting a swirling motion to the incoming combustion air, acts to direct more of this combustion air through ports formed in an inlet portion of the burner head. Thus, more primary air that enters through these ports is able to mix with the combustion gas over a greater distance prior to the mixture of air and gas exiting from the burner head.